In power supply equipment such as power lines and electric power substations, maintenance/inspection has hitherto been visually carried out mainly by a worker for inspection. In some installation environment or scale of the power supply equipment, however, satisfactory maintenance work cannot be carried out. For example, in power supply equipment in a place between mountains, a high place, or a cold district of much snowfall, work burden at the time of inspection is large, and, in some weather or the like, inspection work is dangerous. In order to solve the above problem, for example, Japanese Patent Laid-Open No. 162280/1998 discloses a power line monitoring system. This power line monitoring system comprises a radio sensor capable of obtaining electric power from a built-in transformer installed in a power line, a receiver/transmitter provided in a power transmission tower, and a photoelectric field sensor which performs photoelectric conversion of sensor output received in the receiver/transmitter and transmits the converted data to a monitoring device provided in an electric power substation through an optical fiber composite overhead earth-wire (OPGW). Light (continuous light) is transmitted from the electric power substation to the photoelectric field sensor through OPGW. The photoelectric field sensor transmits light modulated based on a signal sent from the radio sensor to the monitoring device through OPGW. This modulated light is analyzed in the monitoring device to obtain information associated with the power line, i.e., information on voltage, current, and conductor temperature.
According to the power line monitoring system described in Japanese Patent Laid-Open No. 162280/1998 noted above, equipment such as a transformer for supplying electric power necessary for the operation should be provided. This leads to an increase in size and an increase in weight of the sensor and thus deteriorates the working efficiency of installation on the site. Further, disadvantageously, the place where the sensor can be installed is restricted. Furthermore, since the state of the power line is detected based on light output and sent from the monitoring device, in order to detect the state of the power line in real time, the operating ratio of the monitoring device should be increased. This poses a problem of increased operation cost.
Accordingly, it is a first object of the invention to provide a small temperature recorder for power supply equipment, which can be easily installed in the power supply equipment without restrictions on installation places.
It is a second object of the invention to provide a temperature recording and controlling system for power supply equipment, which can reduce the operating ratio of a monitoring device during power transmission in a normal temperature range and, upon the occurrence of an abnormal phenomenon such as abnormal heat generation in the power line, can promptly send information on this fact.